Optical protective device



'NOV- L. a. REDSTCNE ETAL 2,262,203

OPTICAL PROTECTIVE DEVICE Filed Feb. 28, 1940 INVENTORS. Lac/75 7". Ekzvsraw hEA/E'Y J Aa zms EULMNE Ekasrm ATTORNEYS;

Patented Nowll, 1941 OPTICAL PROTECTIVE DEVICE Louis a. mum, Henry J. Abrams, and Soloman E. Redstone, Detroit, Mich.

Application February 28, 1940, Serial No. 321,260

ZOlaims.

This invention relates to an optical device installed in a door, wall or the like and permitting a person on the inside of the door or wall to inspect a person on the outside of the door or wall before permitting such person to enter or transact business.

An important object of this invention is to provide a novel optical protective device especially adaptable for the entrance doors of dwellings, apartments and ofllces where it is desirable to inspect a person or view the area outside of the door before opening the door. An important feature of the invention is the provision of special optical lenses in the device enabling a wide area in front of the door to beviewed from inside the door. Moreover, the lenses are so formed and mounted that it is impossible for a person being viewed to determine that he is under observation.

Another important object of this invention is to provide an optical guard for doors which is constructed of few parts easily and quickly assembled into a unit and installed in a door or wall. Another important object of this inven-. tion is to provide such a device which can be manufactured and installed at low cost so that the entire cost, including installation, is relatively inexpensive and within the purchasing power of home and apartment owners.

Another important object of this invention is to provide an optical door guard which is combined in a novel way with an ornamental or decorative plate on the front side of the door and serving not only to improve the appearance of the door but also to conceal and harmoniously blend the optical instrument into the decorative appearance of the door. In one important instance the optical instrument of the present invention is associated with a door knocker and the objective lens of the device is designed to fit into the appearance of the door knocker. In another instance, the instrument of the present invention is associated with a name plate secured to the front side of the door.

Various other objects, advantages and meritorious features of this invention will become more fully apparent from the following specification, appended claims and accompanying drawing, wherein:

Figure 1 is a plan view of a front of a knocker plate on a door illustrating a manner of combining the optical door guard of the present invention with the knocker plate,

Fig. 2 is a vertical cross-sectional view throug the center of the knocker plate in Fig. 1, illustrating the manner of combining the optical door guard of the present invention with the knocker.

plate,

Fig. 3 is an enlarged sectional view through the center of an optical door guard constructed in accordance with this invention showing the manner of mounting same in a relatively thick door.

Fig. 4 is a plan view of the front of a nameplate on a door showing the manner of associating the optical door guard therewith, and

Fig. 5 is a vertical section through the center of the name plate of Fig. 4 showing the way of mounting the optical door guard in a relatively thin door.

Referring to the enlarged detail view in Fig. 3, the device in general comprises a tube I 0 extending from one side of a door I2 to the other and containing therein a lens system which provides the viewer on the inside of the door with a wide range of view of the area in front of the door. The lens system includes a comparatively large objective lens ll of plano concave formation mounted in the front end of the tube Ill and being a diameter substantially that of the inner wall of the tube. A smaller lens IS in the rear end of the tube serves as an eye piece for the system. Novel means hereinafter described supports the lens It so that it is in axial alignment with the objective lens and at the proper distance to form an image producing system. Due to the formation of the objective lens it, a gide angle of view is obtained in front of the cor.

Although the lenses may be composed of glass ground to the desired formation, it is preferred to use a transparent plastic material such as Lucite. Material of this kind is relatively inexpensive and effects a substantial saving in the cost of the material for the device.

The larger objective lens I4 is fixed in the front end of the tube by the provision of novel retaining means. At substantially the distance from the front end of the tube equal to the thickness of the lens l4, the tube is provided with an inwardly extending crimp or recess l8 encircling the tube. The crimp forms a circumferential retaining wall preventing the lens from shifting toward the center of the tube.

The front end of the tube I0 is provided with an outwardly extending radial flange 20. A flat ring-shaped member 22 has an outer marginal portion bent over the edge of the flange and secured to the tube in this manner. The hole in the ringshaped member 22 is of' slightly less diameter than that of the lens It so that when the member is properly mounted on the front end of the tube it projects radially inwardly sufficiently far to overlie the rim of the lens and serve as a retaining wall preventing the lens from falling out of the tube.

When the tube assembly is installed in a door such as that illustrated in Figure 3, a supporting plate 24 having an ornamental finish is mounted over the opening of the door through which the tube extends. This plate is provided with a circular hole preferably of approximately the same diameter as the lens M. The ornamental plate overlies the ring-shaped member 22 substantially concealing it from view. When secured to the door it draws the parts of the tube assembly compactly together as is evident in Figure 3.

In the modification of the invention illustrated in Fig. 3, a sleeve 26 surrounds the tube and is provided with an outward radially extending flange 28 adapted to abut the inside surface of the door. The sleeve is slidable on the tube. Doors are of variable thickness and when the tubeis installed in a door of a given thickness,

the sleeve is adjusted along the tube until the flange 28 abuts the inside surface of the door. The flange is then secured by screws or otherwise to the door. The door is preferably drilled out to a diameter equal to the outside diameter of the sleeve 26 as indicated in Fig. 3. The sleeve then also serves to hold the tube in axial alignment with the drilled passage.

The lens l6 serving as the eye piece is mounted coaxially with the larger lens It, as previously mentioned. This is accomplished by the provision of two flat ring-shaped elements 30-40 of slightly less diameter than the tube and mounted side by side. The elements are each provided with a central circular hole. The marginal edges of the elements around the holes are flared outwardly away from one another to form a circular seat. The rim of the lens I6 is received in this circular seat and secured against movement therein. Fastened to the inside end of the tube It in any suitable way is a centrally apertured plate 32. To this plate the elements 3030 I are secured by screws, as indicated. One screw is extra long and serves as the pivot for a swing-- able closure member 34 having a knob 36 to facilitate its movement. The closure member 34 serves as a protective cover for the eye piece preventing damage thereto during non-use.

In Figs. 1 and 2 the optical device is combined in a novel manner with a door knocker. As shown in these figures, the knocker includes a base ornamental plate 38 and a knocker member 40 hinged to the plate'at 82. The tube assembly extends through the door with the front end opening out to the rear side of the base plate 38. A circular hole 44' is provided in the base plate opposite the front end of the tube exposing the objective lens [4 to view. If the base plate .of the door knocker lies flat against the door, it is preferable to counter-sink the outside of the door around the passage drilled through the door in order to recess the retaining member 22 and the flange 20 back from the front side of the door in the manner shown in Fig. 2. The result is a construction wherein the optical device is inconspicuously mounted in the door and harmoniously combined with thedesign of the door knocker.

For narrower doors, a slightly difierent construction is used. The tube I0 is preferably made shorter and the lenses l4 and lfi'are brought closer together. It will be found necessary to make the lens I6 proportionately more conve the closer the two lenses are brought together. Fi ure 5 illustrates the insulation in a door panel 46 of comparatively narrow width. The front end of the tube is preferably concealed by a deborative plate similar to that shown in Figure 3 or by a name plate like that shown at 48 in Figure 4. In the latter case the plate is, grooved at 50 for the reception of a name card.

The rear end section of the tube Ill projects beyond the rear side of the door. In place of a sleeve 26 in Fig. 3, the tube is preferably held to the door and protected from abuse by a coni-- cal shaped ornamental cover 52 secured at its wider end to the rear side of the door and at its narrow end to the rear end of the tube: On its narrow end the cover may carry a closure member like that illustrated in Figure 3 to protect the eye piece.

What we claim is:

1. An observation device for doors, walls and the like comprising, in combination, a metal tube approximately equal to or greater in length than the thickness of the door or wall in which it is to be used, a flange on one end of said tube projecting outwardly away from the tube on all sides, an objective lens of plano concave formation having a diameter substantially that of the inside of the tube and positioned in said end thereof with the plano face thereof flush with the outer face of said flange, said tube integrally formed with a shoulder extending around the tube on the inside surface at a distance from said end of the tube equal to the thickness of the objective lens and forming a seat therefor preventing the lens from movement toward the interior of the tube, a flat plate having its outer marginal portions folded over the edges of said flange for securement thereto and having a circular aperture slightly less in diameter than said lens predisposed coaxially therewith so that the inner marginal portions of the plate around the aperture form a narrow retaining wall preventing the lens from falling out of the end of the tube, an eyepiece of less diameter than said tube,

and a pair of plates in the opposite end of the tube provided with aligned apertures slightly less in diameter than that of the eyepiece and overlapping upon the marginal portions of the opposite sides of the eyepiece to supportthe latter within the tube on the axis of the objective lens and at such a distance therefrom to provide an image producing lens system.

2. An observation device for doors, walls and the like comprising, in combination, a metal tube approximately equal to or greater in length than the thickness of the door or wall in which it is to be used, a flange on one end of said tube projecting outwardly radially away from the tube on all sides, an objective lens of plano concave formation having a diameter substantially that of the inside of the tube and positioned in said end thereof with the plano face thereof flush with the outer face of said flange, said tube provided with an inwardly extending crimp all the way around its body at that distance from said end of the tube equal to the thickness of the objective lens and forming a seat therefor preventingthe lens from movement toward the interior of the tube, a flat metal plate having its the aperture form a narrow retaining wall holding-the lens within the tube against the seat formed by the crimp, an eyepiece lens of less diameter than that of the inside of the tube, a pair of plates in the opposite end of the tube provided with aligned apertures slightly less in diameter than that of the eyepiece and overlapping upon the marginal portions of the opposite sides of the eyepiece to support the latter within the tube on the axis of the objective lens and at such a distance therefrom as to form an image producing lens system, headed fastening pins extending through said eyepiece supporting plates securing th same together, one 01' said pins projecting from the end 01 the tube. and a cover elementpivoted to said projecting pin and swingable from a position at one side of said eyepiece to a position over the same.

LOUIS G. REDSTONE. HENRY J. ABRAMS. SOLOMAN E. REDSTON'E. 

